A central qustion in biology is how the nervous system generates behavior. Answers are being sought in insects, which have relatively simple nervous systems and stereotyped behavior. Specifically, the studies concern the acoustically generated evasive maneuvers made by moths in response to the echolocating cries of bats. Four types of experiments are planned: 1) Interneurons in moth brains respond to acoustic stimulation and show various forms of long-term instability. This may indicate the operation of a mechanism of attention, and will be investigated further. 2) These studies also suggest that the brain plays a regenerative function potentiating (or suppressing) reflex neuronal systems in the thoracic ganglia. A search will be made for descending neural pathways implied by this hypothesis. 3) The evasive behavior of moths consists of turning away in flight from an ultrasonic source. Plans are afoot for a closer study of this behavior in the laboratory. 4) Acoustic detectors are widespread in insects, and two novel mechanisms of hearing were discovered in the preceeding grant period. The site of these detectors and their mode of operation will be sought.